Field of the Invention
The present invention is related to a pattern irradiation apparatus, and particularly to a pattern irradiation apparatus including a phase modulation spatial light modulator.
Description of the Related Art
Pattern irradiation apparatuses have conventionally been known that form an arbitrary pattern of light on a sample plane by using a spatial light modulator (SLM) of a phase modulation type, such as LCOS (Liquid Crystal on Silicon).
In a pattern irradiation apparatus using an SLM of a phase modulation type, an SLM arranged at position conjugate (referred to as an pupil conjugate position hereinafter) with a pupil of objective modulates the phase of light from the light source so as to form a pattern of light (referred to as an irradiation pattern hereinafter) having an arbitrary spatial intensity distribution on a sample plane by utilizing diffracted light generated by the SLM.
However, due to diffraction efficiency, incident light is not emitted in its entirety from an SLM as diffracted light and 0-order light that is not diffracted by the SLM is also emitted together with the diffracted light. This results in a situation where spot P2 is formed by the 0-order light that is focused on the optical axis on sample plane SP in addition to irradiation pattern P1 formed by the diffracted light as shown in FIG. 1A.
A device for example disclosed by Japanese Laid-open Patent Publication No. 2001-272636 includes a 0-order light shutoff plate for shutting off 0-order light on the optical axis immediately before a sample in order to eliminate the above influence of 0-order light. By arranging a 0-order light shutoff plate 1 in the vicinity of the focusing position of 0-order light so as to shut off 0-order light, it is possible to form only desired irradiation pattern P1 on sample plane SP as shown in FIG. 1B.